Reinforcing fillers are conventionally used in rubber compositions which are, in turn, used as components for various rubber products, including tires and industrial products, including belts and hoses.
Carbon black aggregates are conventionally used for such filler, although precipitated silica aggregates are also sometimes used. Usually a coupling agent is used with the silica to enhance the silica's reinforcing effect for the elastomer. Such reinforcement of rubber compositions is well known to those skilled in such art.
It is to be appreciated that carbon black for rubber reinforcement purposes are typically used in a form of irregularly-shaped aggregates composed of a multiplicity of primary carbon black particles. Usually, the primary carbon black particles themselves are somewhat spherically shaped although they may also be irregularly shaped. Such carbon black aggregates and their use as rubber reinforcement is well known to those having skill in such art.
Hollow silica particles for use in rubber have been disclosed in WO 97/40105 as being prepared by precipitating active silica onto a core material other than silica and then eliminating such core material.
Hollow aerogel microspheres have been disclosed in U.S. Pat. No. 5,227,239 as being prepared by reacting a metal oxide with water and base catalyst in alcohol solvent to result in an alcogel, injecting an inert gas into drops of such alcogel to form hollow alcogel microspheres followed by supercritically drying such alcogel.
Hollow spherical shells prepared by flame combustion is disclosed in U.S. Pat. No. 3,161,468.
Preparation of hollow glass spheres is disclosed in U.S. Pat. No. 4,257,799.
Preparation of hollow porous microspheres from dispersed particle compositions is shown in U.S. Pat. No. 5,397,759.
Preparation of hollow gelled spheres from aqueous sol of ceramic material is shown in U.S. Pat. No. 5,492,870.
It is desired herein to provide for the preparation of a novel filler for rubber compositions, novel rubber compositions and novel products containing at least one component of such rubber composition.
The term "phr" where used herein, and according to conventional practice, refers to "parts of a respective material per 100 parts by weight of rubber, or elastomer".
In the description of this invention, the terms "rubber" and "elastomer", where used herein, may be used interchangeably, unless otherwise prescribed. The terms "rubber composition", "compounded rubber" and "rubber compound", if used herein, are used interchangeably to refer to "rubber which has been blended or mixed with various ingredients and materials" and such terms are well known to those having skill in the rubber mixing or rubber compounding art.